In that case, you have 3 options for dealing with the 1:85:1 scenes:
1. Crop the top and bottom of the picture until the active image is the same vertical size as the 2:35:1 picture. You may end up cutting off tops of heads, etc.
2. Resize the picture vertically until it's the same height as the 2.35:1 picture. You will end up with an incorrect aspect ratio, short/fat actors and so on.
3. Resize the picture both horizontally and vertically. The aspect ratio will be correct, you will not have cropped any image, however you will need to add black borders to the left and right of the active image.
Or you could use a combination of all 3 methods; try and find a compromise that you're happy with.